Preparation of alcohols from carboxylic acids



ruthenium dioxide catalyst.

-ruthenium raccal, alumina, kieselguhr, etc. Y

catalysts may be prepared,V by the method disclosed ,in U. Sg-,Patent 2,079,404,01` by other'` This reaction mixture was shaken and heated at 200 C. under 200 atm. of hydrogen pressure for 4.5 hours. Fractionation of the filtered product resulted in the isolation of ethanol inl-11% conversion and ethyl acetate 17% conversion; Y

l Example V A 40G-ml. shaker tube was charged with 252g. -f

(2.0 moles) of oxalic acid dihydrate and 3.8 g.A

of ruthenium dioxide catalyst. This mixture lwas heated with shaking at S14-170 C. under 630-990 atm. of hydrogen pressure for 10.5 hours. Fractional distillation of the filtered product resulted in the recovery of ethylene glycol'in 47%conversion. Ethanol was a by-product.

` Emample VI Y A 40G-ml. shaker tube was charged with 118 gf (1.0 mole) of succinic acid and 1.8 g. of ruthenium ,dioxide catalyst. 'This mixture was heated Vwith shakingat 152-192" C. under 720-950`atm. Vof

hydrogen pressure for Vlfhours. By fractionating 'the 'filtered product, tetramethylene glycol was obtair'ied in.59% conversion. By-products of the Vreaction included propanol and butanol.

. `The examples have illustrated certain specific preferred conditions of temperature, pressure,

catalyst concentration, etc., It is to lbe underfstood, however, that these, are all interdependent variables and that variation of one often requires compensating adjustments in the others.Y

In the practice ofthis invention, .any ruthemum-containing catalyst can be employed. Ex-

amples are elementary ruthenium, ruthenium Voxidessuch as the sesquioxide, dioxide, and tetraoxide, salts of rutheniumvsuch as barium per- V,ruthenita' sodium perruthenite, etc.; ruthenates such as sodium, potassium, barium,` silver, cal- .40

cium, strontium, and magnesiumv ruthenates, etc.; perruthenates such afs potassiunand sodium perruthenates, etc.; ruthenium halides such `as dichloride, ruthenium trichloride, ruthenium tetrachloride, ruthenium pentai'luoride', etc.; ruthenium chloro salts such as' potassium chloro perruthenate, etc.; ruthenium sulil'd'es such as ruthenium disulde and trisulde. etc.;V A ruthenium sulfate, etc. The preferred vrutheniurm catalysts are elementaryruthe'nium and the ruthenium oxides because ofthe superior lresults in point of yield obtained therewith." f

Optimum results are obtained in batch operpoint of reaction..ratesandvyield of desired alcov'hol are obtained within thei'range ofl120200 C.,

this constitutes the preferred temperatures of operation. Y I

The process may be operated as a batch or VAas, a semic'ontinuous or continuous operation.

'In general, the hydrogenation is effected in the absence of a solvent or diluent; but, if desired,

i an inert medium such as water or hydrocarbons can be employed.

The process of this invention makes it possible tovconvert any unsubstituted aliphatic monoor dicarboxylic acid to an alcohol. By unsubstituted aliphatic mono or dicarboxylic acid is meant any aliphatic carboxylic acid containing Afrom l to 2 carboxyl 'groups and which, except for the oxygen of the carboxyl group, ris wholly hydrocarbon. Examples of suitable Yacids are acetic, propionic, isobutyric, caproic, `caprylic, laurie, myristidfstearic, arachidic, Vcerotic, oleic, linoleic, Ibeta-eleostearic, rv`crotonic, undecylenic. succinic, adipic, .sebacic, oxalic; and thevlike. Thus the alcohols obtained from these acids are as follows: ethanol from acetic acid, n-propyl alcohol from propionic acid, `isobutyl alcohol from isobutyric acid, n-hexyl alcohol from caproic acid, n-octyl alcohol from caprylic acid, lauryl f alcohol fromlauric acid, myristyl alcoholfrom divided form. When it is desired-to employ Very low catalyst concentrations, it is f advisable to extend the ruthenium on a support such as char- Such .supported methods involving reductionof la compound Yof Yruthenium inthe presence of a carrier substance.

.The amount of ruthenium catalyst,l calculated 'ias ,thezdioxida can vary between 0.5% and 10% superatmospheric pressures of at least 200 atmospheres. As a rule, however, better reaction rates areY attainedA employingV4 pressures in excess of 500 atm.j The use of pressuresin excess of 1500 atm;` does not appear toA have any advantageand myristic acid, octadecyl alcohol from stearic, oleicflinoleic and beta-elecstearic acids; eicosyl *alcohol -from arachidic acid,"ceryl alcohol from cerotic acid, n-butyl alcohol fromcrotonic acid, undecyl alcoholfrom undecylenic acid, tetra#l methylene glycol rfrom succinic acid,l hexamethylene glycol from adipic acid, decamethylene glycol from sebacic acid,and ethylene glycol vfrom oxalic acid.V If desired, mixtures of acids-*may be processed to produce mixtures' of alcohols, and suitable mixtures are those obtained byhydrolysis of naturally'occurringoils and fats. w l `The' process offthis` invention represents a. marked improvement over previously used methods because it makes possible the direct conversion of aliphatic carboxylic acids to the corresponding alcohols in high yields and with minimum of by-product formation at low temperatures. A's many 'apparently widely diiferent embodiments of this inventionV may be made without departing :fromv the spirit and scope'thereof, it is to beunderstood that this invention is not limited tothe specic 'embodimentswthereof except as denjed'in theappendedclaims.' 'y

Iclaim: w f 1. A process forfthe preparation of analiphatic alcohol whichY comprises reacting hydrogen with an unsubstitutedaliphatic carboxylic acid, :inthe liquidf phase under a pressure of at `least 200 atmospheres lat a temperature within the range of 'to 300 C. and in'v contact with a rutheniun'icontaining hydrogenation catalyst, saidhydro'gen being the 'sol'e component o'f the initial reaction mixture capable' of reacting with said'carboxylic acidV and sep'aratinganaliphatic lcohol from the reaction mixture.

2. A process for thepre'parationof an aliphatic alcohol which comprisesreacting hydrogenzwith an unsubstituted aliphatic monocarboxylicacid,

in the liquid phase .under a pressure of at leastV 200 atmospheresat a temperature withinth'e 5 range of 90 to 300 C. and in contact with a ruthenium-containing hydrogenation catalyst, said hydrogen being the sole component ofthe initial reaction mixture capable of reacting with said monocarboxylie acid, and separating an aliphatic alcohol from the reaction mixture.

3. A process for the preparation of ethanol which comprises reacting hydrogen with acetic acid, in the liquid phase under a pressure of at least 200 atmospheres at a temperature within the range of 90 to 300 C. and in contact with a ruthenium-containing hydrogenation catalyst, said hydrogen being the sole component of the initial reaction mixture capable of reacting with said acetic acid, and separating ethanol from the reaction mixture.

4. A process for the preparation of ethanol which comprises reacting hydrogen with acetic acid, in the liquid phase under a pressure oi' at least 200 atmospheres at a temperature within the range of 90 to 300 C. and in contact with a ruthenium dioxide hydrogenation catalyst, said hydrogen being the sole component of the initial reaction mixture capable of reacting with said acetic acid, and separating ethanol from the reaction mixture.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,839,974 Lazier Jan. 5, 1932 2,079,404 Harris May 4, 1937 2,322,095 Schmidt June 15, 1943 2,456,633 Haensel Dec. 21, 1948 2,478,261 Frank Aug. 9, 1949 2,487,054 Howk Nov. 8, 1949 

1. A PROCESS FOR THE PREPARATION OF AN ALIPHATIC ALCOLHOL WHICH COMPRISES REACTING HYDROGEN WITH AN UNSUBSTITUTED ALIPHATIC CARBOXYLIC ACID, IN THE LIQUID PHASE UNDER A PRESSURE OF AT LEAST 200 ATMOSPHERES AT A TEMPERATURE WITHIN THE RANGE OF 90 TO 300* C. AND IN CONTACT WITH A RUTHENIUMCONTAINING HYDROGENATION CATALYST, SAID HYDROGEN BEING THE SOLE COMPONENT OF THE INITIAL REACTION MIXTURE CAPABLE OF REACTING WITH SAID CARBOXYLIC ACID AND SEPARATING AN ALIPHATIC ALCOHOL FROM THE REACTION MIXTURE. 